Bit and core breaker



Shepo 14, 1937. o. HAMMER $939945 BIT AND GORE BREAKER\ Filed sept. 17, 1954 3 sheets-sheet 1 rql.

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BIT AND CORE BREAKER Filed sept. 17, 1934 5 sheets-sheet 2 v Inman/0r.

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Sept. 14, 1937. o. HAMMER 993,945

BIT AND GORE BREAKER Filed Sept. 17, 1954 3 Sheets-Sheet 5 721/ V622 foi" @Hammer @f y l 31 vfio Patented Sept. 14, 1937 UNITED STATES PATENT OFFICE BIT AND CORE BREAKER Application September 17, 1934, Serial No. 744,327

2 Claims.

My invention relates to improvements in well drilling bits.

An object of the invention is to provide a well drilling bit having cutting edges designed to cut the formation about a core, the axis of which is coincident with the axis of rotation of the bit and to provide a suitable core breaker which will break up or cut away the core as it is formed. The invention is particularly applicable to well drilling bits of the sh tail type or that type of bit having outwardly extending blades. Bits of this general character have been found to be most eiflcient for average well drilling although under certain conditions other types of bits have proven more satisfactory.

An object of the present invention is to preserve all of the advantageous characteristics of a fish tail bit and in addition thereto to supply a suitable core breaker or'core cutter.

In well drilling bits of the sh tail type diculty is sometimes experienced by the blades of the bit cutting around a central conical core which, because of its being located immediately beneath the axis of rotation, is sometimes difficult to break up. The result is that the core has a tendency to support the bit at its center, making it diicult to proceed through the formation because of the bit riding on the central core. The formation of the core also is conducive to cause the bit to walk around the bottom of the well hole, resulting in a tendency to form crooked holes particularly where the dip of the formation is such as to tend to divert the bit from its vertical path. The improved bit with its core breaker adequately and satisfactorily cuts away or breaks away the core as fast as it forms.

Another object of the invention is to provide a bit of the sh tail type with adequate bearing areas at the inner ends of the blades which will bear against the sides of the core and extend partially around it, thus having a stabilizing effect.

A further object of the invention is to provide a well drilling bit of the sh tail type wherein there are radial cutting blades with helically shaped cutting edges on the outer and inner sides of the blades, the outer cutting edges serving to adequately ream the hole to gauge and the inner cutting edges serving to scarify the core.

With the foregoing and other objects in View, which will be made manifest in the following detailed description, and specifically pointed out in the appended claims, reference is had to the accompanying' drawings for an illustrative embodiment of the invention, wherein:

Fig. 1 is a top plan view of one form of bit embodying the invention.

Fig. 2 is a view in side elevation of the same.

Fig. 3 is a View in end elevation of the bit shown in Fig. 1.

Fig. 4 is a sectional View taken substantially upon the line 4-4 upon Fig. 2.

Fig. 5 is a bottom planV View of the bit shown in Fig. 1.

Fig. 6 is a View in side elevation illustrating an alternative form of construction embodying the invention.

Fig. 7 is a partial view in end elevation of the bit shown in Fig. 6.

Referring to the accompanying drawings, wherein similar reference characters designate similar parts throughout, the invention, as embodied in one of many alternative forms, consists of a body I0 having a threaded pin II providing for attachment to the bottom end of a drill pipe or a drill collar. This body is of a general sh tail type having outwardly extending blades generally designated at I2 and I3. In the preferred form of construction each blade has its outer side forming its reaming edge provided with a rearwardly extending ange or extension I4 which effectively widens the outer end of each blade. VIn a similar manner, the inner end of each blade is formed with a rearwardly extending flange or extension I5 which is curved and which is preferably of a general semi-conical shape. These flanges or extensions l5 on the inner ends of the blades present relatively wide bearing surfaces which will ft about the cone of the core which is left by the cutting edges I6 on the blades. They are formed with helically shaped cutting edges or teeth I1, which cutting edges curve upwardly and rearwardly from the forward face of each blade, conforming in Vshape to a conical helix. The teeth may also be compared in shape to large tapered threads which are arranged one above the other with the teeth as they progress upwardly approaching the Vertical, central axis or the axis of rotation of the bit.

The pin II is preferably cored out as indicated at I8 and a vertical, central port I9 is formed in the body which is co-axial with the axis of rotation. This port is arranged to discharge circulation fluid centrally of the core which is left by the cutting teeth I6 and to wash out cuttings developed by the teeth Il scarifying away the sides of the conical core. Additional ports 20 may be formed in the body arranged to discharge the circulation fluid over the forward faces of the blades.

The invention as above described consisting of the inner teeth I1 helically formed so as to conform to a conical helix may be applied to any type of well drilling bit which is rotatable about its vertical central axis and where it is desired to cut away or remove the core. I find it, however, advantageous to use the invention on a bit which is provided with outer toothed reaming edges such as are disclosed in my copending application 60 Serial No. 744,326, i'iled September 17, 1934. These reaming edges are provided by a series of teeth 2l extending across the end faces of the blades and across the extensions I4. These teeth, in the preferred form of construction, are upwardly and rearwardly curved in conformity to a cylindrical helix or approximately of that shape. Their function is to ream the walls or the well out to gauge. The cutting portions of the blades IS may be given a small plow shape, as clearly shown on Fig. 5, although the particular form or shape of these cutting portions may vary. When given this plow shape they are effective to plow up the formation around the central core. Both the inner teeth Il' and the outer teeth 2l are downwardly and forwardly inclined in the direction of rotation and because of their inclination both the inner and outer teeth will scarify, that is, the outer teeth 2| will scarify and ream the walls of the well, whereas the inner teeth l'l will scarify and cut away the core. By virtue of the fact that the inner teeth are formed over relatively wide curved surfaces formed by the extensions or fdanges l5 these teeth, during their engagement with and scariiying action on the core, tend to stabilize the bit and prevent walking and also tending to prevent deviation of the bit from the vertical or intended direction. The stabilizing tendency of the inner teeth l? is assisted by the wide surfaces afforded by the flanges lli on which the teeth 2! are formed.

As will be noted from an inspection of Fig. 2, the cored opening 22 on the back of each blade disposed between flange I4 and flange l5 is of such shape as to cause flange lf3- opposite the backs of teeth 2l to be of substantially the same horizontal thickness. In the event that the bit should wear severely the intention of such a construc tion is that no additional metal will be present near these reaming teeth which would form a large metal surface on the bottom of the worn bit which would have to be worn off before drilling could proceed. In other words, it is desired to present the same amount of metal on the bottom of the bit regardless of where it may have worn across teeth 2l.

In the alternative form disclosed in Figs. 6 and 7, the blades 3i! and Si are considerably wider at their cutting edges than the blades as shown in Fig. 2. They still have, however, the rearwardly extending extensions 32 and 33 on each blade with the outer reaming teeth 34 formed on the end edges of the blades and extending across their extensions and the inner core cutting l55 teeth 35 formed across the inner edges of the blades and across the extensions 33. In this form of construction, also, each blade has its forward face plow-shaped with an upwardly extending central projecting rib or edge 3E. In this form of construction, also, the outer teeth 34 are helically shaped to conform to a cylindrical helix and the inner teeth 35 are helically shaped in conformity with a conical helix. The inner teeth serve to scarify and cut away the core while the outer teeth ream. In this type of construction the lower ends of the lowermost core cutting and reaming teeth terminate at the very bottom of each blade so that these teeth become effective on the core and on the walls of the well as soon as the formation is penetrated by the bottom cutting edges 37.

In Figs. 6 and '7 the cutting blades, the core cutting teeth, and the reaming teeth are shown as having been formed on a part separate from the body, which is indicated at 38. 'I'his part has a transversely extending rib or tongue 39 at its top extending into a groove 45 at the bottom of the body or shank. Laterally extending holes are formed in the bottom of the shank opposite the sides of the groove or recess 40. rIhese holes are of varying size or diameter. As shown on Fig. 7, one end of each hole, as indicated at 4l, is large. The opposite side of the hole, indicated at 42, is somewhat smaller, but the axis thereof is in alignment with the axis of the end 4l. Holes 43 are formed in the rib or tongue 39 and the axis of each hole 43 is eccentric with respect to the axes of holes 4I and 42. Its size is such that when the parts are assembled hole 43 is within the circumference of hole 4l. Bolts are provided, each bolt having a head 4:3 which is recessed in the side of the shank and the shank of a bolt has a large end near the head which fits hole 4I. It has an eccentric portion which will t hole 43 in the rib and a small end which nts hole 42. These bolts can be inserted and the eccentric portion caused to enter and t in the eccentric hole 43. Nuts 45 are screwed on to the bolts and are pinned against loosening as by pins 46.

The advantage of the eccentric portion fitting the eccentric hole 43 is such that if the bolt tends to turn, the eccentric tends to tighten and thus more firmly attach the portion providing the blades and teeth to the shank 38.

From the above described constructions it will be appreciated that the invention may be incorporated in various styles of bits, such as for example, bits commonly known as drag bits or even in the shanks of rotary disk bits. The helically shaped teeth l1 and 35 may be employed on any type of bit where it is desired to scarify and break up the core formed under the center of the bit to prevent the body of the bit from riding thereon.

Various changes may be made in the details of construction without departing from the spirit or scope of the invention as dened by the appended claims.

I claim:

1. A well drilling bit having cutting blades, the inner and outer sides of the blades being formed with teeth arranged one above Vthe other and which are helically curved, the outer teeth being formed to conform to a cylindrical helix and serving to ream the walls of the well, and the inner teeth being formed to conform with a conical helix and serving to cut the core left by the cutting edges of the bit.

2. A well drilling bit having cutting blades,

the inner and outer sides of the blades being formed with teeth arranged one above the other and which are helically curved, the outer teeth being formed to conform to a cylindrical helix and serving to ream the walls of the well, and the inner teeth being formed to conform with a conical helix and serving to cut the core left by the cutting edges of the bit, the teeth of both sets being curved upwardly in thesarne direction about the vertical central axis of the bit.

OTTO HAMMER. 

